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    <title>Document</title>
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<script>
  function timeoutPromise(delay){
    return new Promise((resolve, reject) => {
        setTimeout(() => {
          //   console.log(1)
          resolve(`延迟了${delay}秒钟`)
        }, delay * 1000)
      })
  }
  const p = timeoutPromise(1)
    .then((res) => {
      console.log(res) // 打印1
      return timeoutPromise(2)
    })
    .then((res) => {
      console.log(res)
      return timeoutPromise(3)
    })
    .then((res) => {
      console.log(res)
      return timeoutPromise(4)
    }).then((res)=> {
      console.log(res)
    })
</script>
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